FactoryBotの定義チートシート

# spec/factories/users.rb

  factory :admin, class: 'User' do
    account_name { 'admin_account' }
  end

# spec/factories/admins.rb

  factory :admin do
    permission_type { :full }
  end

# spec/factories/users.rb
FactoryBot.define do
  factory :user do
    name { 'suzuki' }
  end
end

build(:user)
User.new(name: 'suzuki')

create(:user)
User.create(name: 'suzuki')

# spec/factories/users.rb
FactoryBot.define do
  factory :admin, class: 'User' do
    name { 'suzuki' }
  end
end

class Book < ApplicationRecord
  belongs_to :author
end

FactoryBot.define do
  factory :book do
    # spec/factories/authors.rb に `factory :author`の定義がある前提
    author
  end
end

class Author < ApplicationRecord
  has_many :books
end

FactoryBot.define do
  factory :author do
    # spec/factories/books.rb に `factory :book`の定義がある前提
    books { Array.new(5) { association(:book) }.compact }
  end
end

FactoryBot.define do
  factory :author do
    transient do
      books_count { 5 }
    end
    # spec/factories/books.rb に `factory :book`の定義がある前提
    books { Array.new(books_count) { association(:book) }.compact }
  end
end

class Author < ApplicationRecord
  has_many :books
end

class Book < ApplicationRecord
  belongs_to :author
end

FactoryBot.define do
  factory :author do
    books { Array.new(books_count) { association(:book) }.compact }
  end
end

FactoryBot.define do
  factory :book do
    author
  end
end

FactoryBot.define do
  factory :author do
    books { Array.new(books_count) { association(:book, author: instance) }.compact }
  end
end

FactoryBot.define do
  factory :book do
  author { association(:author, books: [instance]) }
  end
end

author = create(:author)
author.books.first.author == author # => true

FactoryBot.define do
  factory :book do
    author factory: :user
  end
end

# spec/factories/users.rb

FactoryBot.define do
  factory :user, aliases: [:author] do
    name { 'suzuki' }
  end
end

class Book < ApplicationRecord
  belongs_to :author, class_name: 'User'
end

# spec/factories/books.rb
# これはうまくいかない
FactoryBot.define do
  factory :book do
    user
  end
end

# こっちはうまくいく
FactoryBot.define do
  factory :book do
    author
  end
end

FactoryBot.define do
  factory :user do
    name { 'suzuki' }
    email { "#{name}@example.com" }
  end
end

class User < ApplicationRecord
  has_many :blogs
  has_many :entries
end

class Blog < ApplicationRecord
  belongs_to :user
  has_many :entries
end

class Entry < ApplicationRecord
  belongs_to :blog
  # blog経由で到達できるがショートカットで外部キーがあるとする
  belongs_to :user
end

FactoryBot.define do
  factory :blog do
    user
    entries { Array.new(5) { association(:entry, blog: instance, user: user) }.compact }
  end
end

FactoryBot.define do
  factory :entry do
    blog { association(:blog, entries: [instance], user: user) }
    user
  end
end

FactoryBot.define do
  # factoryメソッドのブロック外である点に注意
  sequence :account_name do |n|
    "account#{n}"
  end
end

FactoryBot.define do
  factory :user do
    account_name { generate(:account_name) }
  end
end

FactoryBot.define do
  factory :user do
    account_name # シーケンスで生成された値になる
  end
end

FactoryBot.define do
  factory :user do
    sequence(:account_name) { |n| "account#{n}" }
  end
end

FactoryBot.define do
  factory :user do
    sequence(:account_name, 50) { |n| "account#{n}" }
  end
end

FactoryBot.define do
  factory :user do
    # :a, :b ... :z, :aa, :ab ...
    sequence(:account_name, :a) { |n| "account#{n}" }
    # 'a', 'b' ... 'z', 'aa', 'ab' ...
    sequence(:account_name, 'a') { |n| "account#{n}" }
    # 同じ値が生成され得るがこういうことも可能
    sequence(:account_name, ['suzuki', 'tanaka', 'saito'].cycle) { |n| "account#{n}" }
  end
end

FactoryBot.define do
  factory :user do
    name { 'suzuki' }
    email { "#{name}@example.com" }

    factory :admin do
      name { 'admin' }
    end
  end
end

FactoryBot.define do
  factory :user do
    name { 'suzuki' }
    email { "#{name}@example.com" }
  end

  # ネストしていないが、parentを指定していることでuserファクトリから属性を引き継いでいる
  factory :admin, parent: :user do
    name { 'admin' }
  end
end

FactoryBot.define do
  factory :product do
    factory :sale_product do
      # セール品の属性が並ぶ

      factory :sale_physical_product do
        # 物理商品の属性が並ぶ
      end

      factory :sale_electronic_product do
        # ...
      end
    end

    factory :regular_price_product do
      # 定価品の属性が並ぶ

      factory :regular_price_physical_product do
        # sale_physical_productのところと全く一緒のものが並ぶ
      end

      factory :regular_price_electronic_product do
        # sale_electronic_productのところと全く一緒のものが並ぶ
      end
    end
  end
end

FactoryBot.define do
  factory :product do
    trait :sale_product do
      # セール品の属性
    end

    trait :regular_price_product do
      # 定価品の属性
    end

    trait :physical_product do
      # 物理商品の属性
    end

    trait :electronic_product do
      # 電子商品の属性
    end

    factory :sale_physical_product, traits: [:sale_product, :physical_product]
    factory :sale_electronic_product, traits: [:sale_product, :electronic_product]
    factory :regular_price_physical_product, traits: [:regular_price_product, :physical_product]

    # 以下のようにトレイトを属性のように書くことも可能
    factory :regular_price_electronic_product do
       regular_price_product
       electronic_product
    end
  end
end

trait :admin_name do
  name { '管理者' }
end

# build(:admin).name # => 'admin'
factory :admin do
  # トレイトと属性の順序に関係なく属性定義の内容が優先される
  name { 'admin' }
  admin_name
end